Machine for dimpling or the like



April 17, 1945. w. KAHLER ErAL 2,374,019

MACHINE FOR DIMPLING OR THE LIKE Filed Nov. 1s, 1942 INVENTORS+ WILL/AM KAHLER FREDHLATHROP ATTORNEYS.

.rear chamber II b-y a partition I3.I

Patented Apr. 17, 1945 PATENT oFFlcE MACHINE Foa DiMrLnG on THE LiKE' William Kamer, vLos Angeles, and 'Fred H.

Lathrop, San f Dimas,

Northrop Aircraft," Inc., corporation of California Calif., assignors to Hawthorne, Calif., a

Application November 13, 1942, Serial No. 465,812

7 claims. (CL-1522+211 f Our invention relates to machines for performying dimpling operations or the like on sheet material, and has for its objects:

(l) To ,provide a novel and improved dimpling machine or the like. f u 5 `(2) To provide a novel and improved dimpling machine or the like wherein the sequential movements of a tool and impact means are inherent in the machine.

.. i 3) .To provide a' nova andimproved dimming@ machine or the like offering maximum assurance to an operator against injury.

. .y .(4) .To provide a novel and improved dimpling machine or the like incapable of functioning in improper sequence, whereby'danger of faulty .op-.,ls eration and breakage of parts is avoided.

. (5) To provide a novel and improved dimpling vmachine orthe like which is convenientlypqrtable lby^the .operator during use. f i A ;Additional objects of our invention will befrbrought out in the following descriptionof a preferred embodiment thereof, taken in conjunction vwith the accompanying drawing Whereinthe gure is a Viewin section through such preferred embodiment of our invention.

'/Thefbody or framework of the machine comprisesa cylinder or barrel I to one end of which vis mounted a yoke 3, While the other end carries a handle 5` depending therefrom.

yTheyoke 3 is of inverted U-shape with one leg ido .vl-thereof recessed and threaded for attachment to the front end of the cylinder or barrel I-.'- vThe cylinderA is divided'into a, front chamber Banda A tool I5, in the form of -a cylindrical'rod, proill vided with an intermediate ilange -.I'I, is reciprocally supported in the front chamber 9 with the'ange Il .acting as a piston therein i One end I9 of the tool slidablyextends through an opening in the recessed portion of the leg 'I of the'yoke a 40 .3'. The rear. portion 2| of the tool. is adapted to @enter an opening 23 in the partition I3 on return )strokes of. the tool. VA compression spring 25 is disposed about the rear portion of the tool ybetween a thrust washer 21 iitting up against the .partition I3, and the rear surface of the ilangel'l. .In the rear `chamber II of the cylinder or .bar-

The machine utilizes compressed airin'its operation, and to this end compressed air is introduced i'ntothe machine through the handle 5 from some '55 external source (not shown) by way of a suitable tfitting 33, and the compressed air is controlled through -a' system of-valves and passages incorporated inthe handle.

The. handle 5 is preferably mounted on the cylinder I .by;sliding one end of thev handle over the end of the cylinder and holding it in position by an end nut threaded into the rear end of the cylinder. The handle includes an air intake passage 31 connecting with the source ofcompressed air 'externally of themachine, and an exhaust passage 39 discharging to the atmosphere at the lower endv of the handle. Both the intake and exhaust passages merge into a common passage 4| entering into the rear chamber I I of the cylinder.

The intake passage 3l is normallylcut on from the common passage 4I by a, spring biased throttle valve'43 having a valve stem 45 protruding slightly beyond the front Wall 4l of the handle. The exhaust passage 39, on the othervhand, is normally maintained in open communication With the vcommon passage 4I by a normally open exhaust valve 49. --Such exhaust valve comprises. a stationary sleeve 5I tted into the handle and intersecting the exhaust passage 39, but having perforations 53 through'the Walls thereof in line with the exhaust passage to permit of normal communication with thel common passage 4I to the cylinder. lA pin 55, slidably'tting in the sleeve 5'I, has a hollow end to receive a compression spring 51 for normally biasing this pin beyond the perforations 53 .in the sleeve to establish the open condition of the valve, with the pin extending beyond -the front Wall 41 of the handle.

The extent to which this pin protrudes beyondthe front Wall of the `handle' is determined by atrigger 59 which is pivoted to the handle adjacent. the cylinder and has its forward swing limited by an integral stop 6I' abutting against the lower surface o'f the cylinder. At its maxi- 'mum forward position, the trggeris in spaced relationship to the exposed endof thethrottle .valve stem 'while the pin 55 of the exhaust valve 'is maintained in pressure contact or engagement with thetrigger by the compression spring 5l of the exhaust valve. Therefore, upon pulling the trigger, the exhaust valve 49 and the throttle valvel 43 Will be operated sequentially in thev order named, such operation bringing Aabout aclosing of the exhaust-valve, followed' by. an openingof the throttle valve. To assure -nriaintenancev of properl alinement between the 'trigger59 and the pin 55 of the exhaust valve,

A restricted air passage 65 is provided, which connects the intake passage 31 of the handle with the front chamber 9 of the cylinder ahead of the tool flange l1. This restricted passage is formed of a bore (i1-through the handle and a bore 69 in the leg 1 of the yoke, connected by a length of tubing 1I. The bore 61vin the handle intersectsthe sleeve l and pin 55 of the exhaust valve. The sleeve is provided with diametrical perforations 13 in alinement with the bore while the pin is formed with a peripheral groove 15 which is so located as to come .into alinement with the perforations 13 in the open position of the valve.

On the cylinder f, just behind the partition I3, we provide a relief valve 11 comprising a hollow integral boss 19 having a cover 8l threaded thereon at its exposed end. This boss is provided with a plurality of air passages 83 extending laterally from the passage 85 through the boss, which passage is of. enlarged diameter be- 4is blocked/by the throttle valve 43, while the discharge passage from the cylinder is open through the exhaust valve 49. Under the same conditions, the fore part of the front chamber 9 is exposed to air under compression. through the restricted passage 65 from the air intake passage in the handle to the front chamber,

thereby causing the tool to be retracted into the cylinder to Vthe maximum extent permitted by -tlie'compression spring 25 behind the flange l1. By providing a loose or leaky fit between the flange -l'l and the inner Wall of the iront chamber, and between the rear portion 2i of the tool and the partition. I3r air will leak over into the rear chamber H and build up a pressure therein suilicient 'to force the piston 29 to the rear end 'of its chamber. The figure of the drawing illustrates thetool in itsv retracted positionv and the piston in the middle of its return stroke.

`The pressure in the rear chamber, howeven if permitted to build up to the extent of equal- `izng .the pressure on` they front surface of the tool flange i1, would free the compression spring 25 of any restraint, vand cause the same to urge the tool to its maximum forwardposition. As this is not desired, the relief valve 11 is designed to open up at a value of pressure somewhere in lbetween that pressure necessary to move the piston 29 back to the rear end of its chamber ll and that value which will provide the proper differential pressure necessary to overcome the spring 25 and hold it in compression. Thus, in the non-operating condition of the machine, the tool will remain in its restricted position, with the piston held against the rear end of its chamber.

A restricted exhaust passage 9i extending from the rear extremity of the piston chamber H and connecting with the exhaust passage 39 through the exhaust valve 49, will preventthe formation of an air cushion behind the piston during movement of the piston toward the rear end of the chamber.

Upon pulling the trigger 59 only to the extent the perforation in the sheet material.

of shutting oi the exhaust valve 49, not; only is the discharge passage 39 blocked, but also the restricted passage to the front chamber 9 of the cylinder. This cut-off of pressure from the front chamber, occasioned by the shutting oli of the supply of air thereto, gradually causes a loss in pressure sufficient to permit'the spring 25 to exercise its function of4 urging the tool to its most forward position.

Further movement of the trigger opens the throttle valve 43, thereby exposing the piston 29 to the full force of the compressed. air entering the intake passage 31 from the external source of supply. The piston is thus thrust forward with full impact against the rear end of the tool, the relief valve 1l functioning during the forward thrust of the piston to preclude the building up of compression in the cylinder ahead of the piston.

. Upon release of the trigger, the piston will be returned to the rear end of its chamber, and the tool will be retracted and held in its retracted position, all as previously described.

Where the machine is to be'. employed for dimpling, the free end 93 of the yoke is perforated to receive the female part 95 of a dlmplle set while the tool is recessed to receive the male component 91.

A sheet of metal to be dimpled is usually provided with a perforation at the. point at which a dimple is to be formed, and such sheet is positioned between the dimpling dies with the perforation in the path of movement of the tool so that during the initial portion of the trigger movement, the tool will be urged forward and the sheet material will be clampedv between the male and female dies with the male member entering The subsequent impact of the piston against the rear endy of the tool, brought about by the completion of the trigger movement, produces the desred dimple in the sheet material, Upon release of the trigger, the dimpling dies will be separated and the material can be removed.

It is apparent that the machine is applicable for other purposes than dimplingl such purposes being realizable merely by the substitution of dies of a different character from those employed for dimpling purposes. Consequently, while the machine has been referred to as employed for dimpling purposes, it is understood that its utility is not limited to this particular purpose. While we have described a preferred embodiment, the same is subject to modification and alteration without departing from` the underlying principles ot ourv invention, and we accordingly do not desire to be limited in our protection to the details cessitated by the appended claims,

We claim:

l. A portable machine for dimpling or the like comp-rising a tool for engagement with work to be operated on, a compression spring normally biasing said tool in. the direction of such work, means normally supporting said tool in spaced relationship to such work against. the action of Vsaid spring under compression; a. hammer for impacting said tool; and control means commori tothe control of said tool and said hammer for removing the restraint upon said spring movement of said tool into engagement with said said spring effective in urging said tool to its forward position against work to be operated on,

3. In a machine for dimpling or the like, a cylinder, a tool reciprocally mounted in one end of said cylinder, a spring in said cylinder normally biasing said tool toward a forward position for engagement with work to be operated on, -means for directing compressed air against said tool in opposition to said biasing spring and at a pressure suilcient to overcome said spring and force said tool rearwardly into said cylinder, means for reducing said air pressure at willA to render said spring eiective in urging said tool to its forward position against work to be operated on, and means for impacting said tool upon its engagement with such work.

4. In a machine for dimpling or the like, a cylinder, a tool reciprocally mounted in one end of said cylinder, a .spring in said cylinder normally biasing said tool toward a forward position for engagement with work to be operated on, means for directing compressed air against said tool in opposition to said biasing spring and at a pressure sufiicient to overcome said spring and force said tool rearwardlyl into said cylinder, means for reducing said air pressure at will to render said spring effective in urging said tool to its forward position against work to be operated on, means for impacting said tool upon its engagement with such Work, and means for restering said impacting means and said tool to their previous positions for a subsequent and similar operation.

, 5. A machine for dimpling or the like comprising a cylinder, a yoke mounted at the front end of said cylinder, a tool reciprocally supported for reducing the air pressure against said tool and creating a sudden increase in air pressure behind said free piston whereby said tool can move in the direction of 'such work and be impacted by said free piston.

6. A machine for dimpling or the like comprising a cylinder, a yoke mounted at the front end of said cylinder, a tool reciprocally supported within said end 'of the cylinder and slidably extending through one side of said yoke, .a spring within 'said cylinder normally biasing said tool within said end of the cylinder and slidably extending through one side of said yoke, a spring within said cylinder normally biasing said tool toward a forward position for engagement with Work positioned between the legs of said yoke. a free piston in said cylinder to the rear of said tool, means for admitting air under pressure against said tool in opposition to said springand at a pressure sufficient to overcome the spring and force said tool to rearwardposition, means providing a leak passage for said air under pressure to the rear of said tool whereby to develop pressure to force said free piston to the rear end of said cylinder, a relief valve inthe wall of said cylinder between said piston and said tool, ad justed to open at a pressure in excess ofythat necessary to force said piston back but sufficiently below the air pressure against said tool to hold said tool at its rearward position, and means toward a forward position for engagement with work positioned between the legs ofsaid yoke, a free piston in said cylinder to the rear of said tool, means for admitting air under pressure against said tool in opposition to said spring and at a pressure sufiicient to overcome the spring and force said tool to a rearward position, means providingA a leak passage for said air under pressure to the rear of said tool whereby to develop pressure to force said free piston to the rear end of said cylinder, a relif valve in the wall of said cylinder between said piston and said tool, adjusted to open at a pressure in excess of that necessary to force said piston back but sufficiently below the air pressure against said tool to hold said tool at its rearward position, and trigger operable means for sequentially reducing the air pressure against said tool and creating a sudden increase in air pressure behind said free pist0n wherebyv said tool will move into engagement with work and be impacted by said free piston.

7. A machine for dimpling or the like comprising a cylinder, a yoke mounted at the front end of said cylinder, a tooi reciprocally supported within said end of the cylinder and slidably extending through one side of said yoke, a spring within said cylinder normally biasing said tool toward a forward position for engagement with work positioned between the legs of said yoke, a. free piston in said cylinder to the rear of said tool, means for admitting air under pressure against said tool in opposition to said spring and at a pressure suiicient to overcome the spring and force said tool to rearward position, means s providing a leak passage for said air under pres-l sure to the `rear of said tool whereby to develop pressure to force said free` piston to the rear end of said cylinder, a relief valve in the wall of said cylinder between said piston and said tool, adl WILLIAM KAI-HIER.v FRED H. LATHROP. 

